Stephenson County showed their patriotism during the Civil War. On April 18, 1861, a meeting was held at Plymouth Hall. Several enlistments were made that night and within two days the first company was filled and ready for muster. A company was recruited at Lena and other parts of the county gave their quotas to the cause.Under the command of Capt. Smith D. Atkins, Lt. Newcomer and Lt. Field, the company left for the front on May 1 and was mustered in as Company A, 11th Reg. Shortly after, a second company under the command of Capt. W.J. McKim, Lt. Settley and Lt. Arno went to the front.

The 15th Reg. was organized in Freeport and mustered in on May 24th. A few weeks later, after receiving instructions at Alton, they left for the field. Their first battle was in Missouri. It was mustered out at Fort Leavenworth on September 1, 1865. Travel by foot, boat and train, a distance of about 11,000 miles was covered. The officers were Col Thomas J. Turner, Senior Major William R. Goddard, Junior Major Rufus C. McEathron, and Surgeon William J. McKim.

The 46th, made up almost wholly of Stephenson County men, was organized at Camp Butler on December 28, 1861, by Col. Davis. He was succeeded after his death at Bolivar, Tennessee on October 10, 1862, by Col Dornblazer. Maj. McCracken and Maj. Clingman were next in command. They were at Ft. Donelson and Ft. Henry, Pittsburg Landing and the campaign through Tennessee. They also participated in the Siege of Vicksburg and marched through to the Gulf. The 46th was mustered in as a veteran regiment January 4, 1863, returned to Freeport and was furloughed on the 27th, seeing no active duty after that.

The 92nd, mustered in at Rockford, September 4, 1862, and contained 3 companies from Stephenson County. It was assigned to the Army of Kentucky. Their first stronghold was on Point Lookout. They participated in battles around Chattanooga, fought under Thomas at Chickamauga, were in the hottest of the fighting in the Atlanta campaign, and swung south with Sherman on the world famous March to the Sea. The 92nd was musted out at Concord, North Carolina and discharged and paid off at Chicago on July 10, 1865, after nearly three years of the hottest fighting in the war. The regiment came out under command of Col. brevetted Brig. Gen. Smith D. Atkins, Lt. Col. Christopher T. Dunham, Adj. Issac C. Dawver and Quartermaster Phillip Sweely. Besides the above, Stephenson County furnished companies of men in the 14th; 26th; 45th; 47th; 71st; 74th; 90th; 93rd; 142nd; for 100 day service, 146th, 1 year service; 147th, 1 year infantry; 7th; 8th; 12th; 13th; 14th and 15th cavalry, and the 1st and 2nd artillery.